To measure the temperature coefficient of resistivity α of a semiconductor, an electrical arrangement shown in the figure is prepared. The arm BC is made up of the semiconductor. The experiment is being conducted at 25 ° C and resistance of the semiconductor arm is 3 m Ω . Arm BC is cooled at a constant rate of 2 ° C s - 1 . If the galvanometer G shows no deflection after 10 s , then α is:

Question

To measure the temperature coefficient of resistivity α of a semiconductor, an electrical arrangement shown in the figure is prepared. The arm BC is made up of the semiconductor. The experiment is being conducted at 25 ° C and resistance of the semiconductor arm is 3 m Ω . Arm BC is cooled at a constant rate of 2 ° C s - 1 . If the galvanometer G shows no deflection after 10 s , then α is:, - 2 × 10 - 2 C - 1 ∘, - 1 . 5 × 10 - 2 C - 1 ∘, - 1 × 10 - 2 C - 1 ∘, - 2 . 5 × 10 - 2 C - 1 ∘

MARKS App · Accepted Answer

For no deflection(balanced condition) 0 . 8 1 = R 3 ⇒ R = 2 . 4 m Ω Temperature fall in 10 s = 20 ° C Δ R = R αΔt ⇒ α = Δ R R Δt = 2 . 4 - 3 3 × 20 = - 1 × 10 - 2 ° C - 1

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